To startup a online business, the first you need to select a Domain Name, which can identify your business and mostly should reflect the objective. Generalized keyword based Domain Names get better SEO ranking and more visitors through Google Search Engine.
But before registering of any of the shortlisted Domain Names, you need to search for conflict with any existing Trademarks as well, which is quite important, given the huge database of Trademarks. You can visit here for Public Search.
Just remember, you cannot register a general word as a Trademark, in a related class. Like you cannot register the word Cyber in Class 42 but in some other class of goods or services.
Class 42. Scientific and technological services and research and design relating thereto; industrial analysis and research services; design and development of computer hardware and software.